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Absolute configuration of four chiral isomers of pyrisoxazole and their bioactivity
Author(s) -
Li Ziliang,
Cong Yunbo,
Ma Xiaohua,
Wei Zhenyun,
Cheng Chunsheng,
Shi Fanian,
Li Sanxi
Publication year - 2020
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.5928
Subject(s) - absolute configuration , fungicide , asymmetric carbon , bioassay , chemistry , carbon fibers , stereochemistry , enantiomer , racemic mixture , stereoisomerism , organic chemistry , molecule , materials science , biology , optically active , botany , genetics , composite number , composite material
BACKGROUND Pyrisoxazole is a fungicide that has two chiral carbon atoms and four isomers: (3 S ,5 R )‐, (3 R ,5 S )‐, (3 S ,5 S )‐, and (3 R ,5 R )‐pyrisoxazole. RESULTS Pure crystals of four pyrisoxazole isomers were prepared by chiral separation and single‐crystal cultivation. Their absolute configurations were established by X‐ray single crystal diffraction analysis. Bioassays indicated that compound (3 S ,5 R )‐pyrisoxazole showed excellent fungicidal activity with a median effective concentration (EC 50 ) value of 0.14 μg mL −1 and protective activity with an EC 50 value of 13.29 μg mL −1 . These values are superior to the commercial fungicides boscalid and racemic pyrisoxazole. CONCLUSIONS The biological activity of racemic pyrisoxazole is due almost exclusively to the isomer (3 S ,5 R )‐pyrisoxazole; the other three isomers had very low activity. © 2020 Society of Chemical Industry